The present invention relates to LED power-source circuits and lamp fixtures using the same.
Because the performance and longevity of light emitting diodes (LEDs) are steadily improving, general purpose light fixtures using LEDs are being more frequently used in place of more conventional incandescent and fluorescent lamps. This trend is expected to continue. Therefore, there is a need for high efficiency LED power-source circuits using DC-DC conversion.
Prior art LED power-source circuits are known for carrying out full-wave rectification of commercial AC power by using a diode bridge, and further carrying out DC-DC power conversion using a DC-DC conversion circuit and a smoothing capacitor, and then supplying the converted voltage to an LED. Also, such prior art circuits may use a configuration in which a circuit ground of the DC-DC conversion circuit is connected to ground via a ground capacitor. However, optimization of the component values of the smoothing capacitor and the ground capacitor has not been considered in detail.